ParisTech

About: ParisTech is a education organization based out in Paris, France. It is known for research contribution in the topics: Residual stress & Finite element method. The organization has 1888 authors who have published 1965 publications receiving 55532 citations. The organization is also known as: Paris Institute of Technology & ParisTech Développement.

Temperature gradient induced instability of perovskite via ion transport

Abstract: Perovskite has been known as a promising novel material for photovoltaics and other fields because of its excellent opto-electric properties and convenient fabrication. However, its stability has been a widely known haunting factor that has severely deteriorated its application in reality. In this work, it has been discovered for the first time that perovskite can become significantly chemically unstable with the existence of a temperature gradient in the system, even at temperature far below its thermal decomposition condition. A study of the detailed mechanism has revealed that the existence of a temperature gradient could induce a mass transport process of extrinsic ionic species into the perovskite layer, which enhances its decomposition process. Moreover, this instability could be effectively suppressed with a reduced temperature gradient by simple structural modification of the device. Further experiments have proved the existence of this phenomenon in different perovskites with various mainstream s...

Numerical Strategy for Forecasting the Leakage Rate of Inner Containments in Double-Wall Nuclear Reactor Buildings

Abstract: In the context of life extension of nuclear reactor buildings while ensuring safety and regulatory requirements, a numerical strategy is proposed to compute and forecast the air leakage rate evolution of inner containments in double-wall reactor buildings under standard long-term operation. In order to reduce the numerical cost of such complex computations, the proposed strategy is based on a coarse but adapted mesh together with a chained weakly-coupled thermo-hydro-mechanical modeling. The total leakage rate is then computed with a specially-designed tridimensional finite element based on a non-linear thermal analogy. This methodology is used to model the behavior of the VeRCoRs mock-up, a simplified nuclear reactor building at scale 1:3, built and monitored by EDF. Results obtained until the first pre-operational pressurization test have been discussed in a dedicated benchmark organized by EDF. The proposed methodology provides delayed strains and leakage results in good agreement with available experimental data. A blind prolongation until the first decennial test of the mock-up is presented and analyzed.

Architectures for Collective Self-aware Computing Systems

Abstract: This chapter aims to discuss the architectural aspects relevant to collectives of self-aware computing systems. Here, collectives consist of several self-aware computing systems that interact in some way. Their interactions may, potentially, lead to the formation of a self-aware collective of systems. Hence, the chapter defines different types of interactions that can link systems into a collective and then discusses the conditions under which self-awareness can be achieved within such collectives. Furthermore, the chapter identifies some of the most relevant architectural concerns that occur when linking multiple self-aware systems into a (self-aware) collective and defines these in the form of a generic meta-architecture for collectives of self-aware systems. Architectural concerns can represent both static and dynamic aspects of system collectives. Static concerns include the self-awareness levels of systems in a collective; the system interrelations, such as competition and cooperation; and several organisation patterns for systems in a collective, such as hierarchy or peer-to-peer designs. Dynamic concerns address changes that may occur over time, with respect to the above-mentioned aspects, based on the experience and learning of systems within the collective. More advanced topics discuss the manner in which the creation of collectives from interrelated systems can be applied recursively, adopting different architectural choices and combinations at each level, and potentially leading to a wide range of variations in the resulting self-awareness characteristics. The chapter concludes by indicating the main contributions and targeted beneficiaries of this chapter and points to the most important challenges to address in future research.

Extraction of Trivalent Lanthanides and Americium by Tri-n-octylphosphine Oxide from Ammonium Thiocyanate Media

Abstract: An investigation of the solvent extraction of trivalent lanthanides and Am3+ from ammonium-thiocyanate media by tri(n-octyl)phosphine oxide (TOPO) in toluene has been completed. This system is of interest both for its potential as a means of separating transplutonium actinides from fission-product lanthanides and for inherent interest in thiocyanate-based solvent extraction systems. Partitioning was monitored using radiotracer techniques where appropriate, and ICP-OES or ICP-MS for others. The extraction behavior of all members of the lanthanide series (except for Pm) plus Y have been investigated. Conditional enthalpies (all exothermic) were determined (for selected systems) from the temperature dependence of the extraction reaction. A comparison with nitrate media shows higher extractive power of TOPO in contact with thiocyanate media, arising at least in part from the lower heat of the phase transfer of thiocyanate (relative to nitrate). The moderate tendency of HSCN to partition into the extr...